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OCR AS - Chemistry Unit F322 - Chains, energy and resource - REVISION!

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Original post by lolo-x
What question was that?


"What is the enthalpy of formation for NO?" (Or something along those lines)
Above the question it had the equation N2 + O2 --> 2NO, with +66 kJmol-1 beside it.

Because enthalpy of formation is the enthalpy change when one mole of a substance is formed, and the equation had 2 moles of NO formed, I divided 66 by 2 = +33 kJmol-1
Ok what about this.

I definitely got ethanol and i drew the structure out.

I think i got propanioic acid and i drew the structure of propanoic acid out but then i wrote it was ethanoic acid.

Then I wrote the ester to be ethyl ethanoate.

Now even though i got the naming wrong but i drew the structures out will I loose many marks here?

How do you think the marks will pan out for the last question?


Btw there was hardly any organic chemistry :/
Reply 782
Avatar for Music22
Music22
Original post by Killmepls
fffffffffs i wrote but 1 ene and crossed it out idk why :frown: aduasfhafna


I hate it when that happens, I crossed the right answer out as well then put a different one too!!!
Original post by maimoonahussain
i hope so
i got the structure right but for some weird reason i called the ester butyl propanoate


Unfortunately if you draw it correctly but name is wrong you don't get the mark :nn:
Original post by DeanFoley
The E/Z isomer was G.

Wait, what question on stereoisomers was there?!


Haha I wish I could say it was a deliberate troll but I meant the structural ones :')
Reply 785
Avatar for Joseppea
Joseppea
OP
2
I was expecting a nice "Name the following molecules" with the whole nomenclature etc. lark that we spent ages learning....... but nooooooo! XD
Original post by sdgvrgverg
It said identify, not draw the structure though..


identify doesn't have to mean the names,
I put the structures and names to be sure,

and I think an ion peak on the last question was useful, helped you to work out where the OH should go, as there was a peak at 31 which would be a CH2OH fragment which means the OH must be on the end,
I hope theres a mark for that
Original post by SmithytheDrummer
Haha I wish I could say it was a deliberate troll but I meant the structural ones :')


Don't you EVER do that to me again!
Reply 788
Avatar for Flint_09
Flint_09
8
Wikipedia!
"Methanol (one carbon), the propanols (three carbons giving two isomers), and the butanols (four carbons, four isomers) are all commonly found alcohols — these three toxic alcohols should never be consumed in any form."
For the last question, did you actually have to draw the structures? I swear it just said to identify the compounds, there didn't seem to be any explicit mention of drawing the structures in the question from what I remember, anyone able to clarify?
Does anyone know what full UMS is on these papers?
Original post by viksta1000
+33

You had to divide by 2 to per enthalpy change per mole


but it gave the unit as KJmol-1 which surely means per mole already...? I just left it as 66 :smile:
Reply 792
Avatar for Ttawwab
Ttawwab
2
Original post by maimoonahussain
i hope so
i got the structure right but for some weird reason i called the ester butyl propanoate


Yeah, I put Methyl Propanoate instead, because I was stupid and got the correct formula for Ethanol, then for some reason thought it was methanol. Hopefully we'll still get the marks. :smile:
Reply 793
Avatar for bagelbe
bagelbe
Original post by racheatworld
Unfortunately if you draw it correctly but name is wrong you don't get the mark :nn:


Really? Because I drew the structure right, but put methyl ethanoate??? :/
Original post by DeanFoley
Don't you EVER do that to me again!


I'm so sorry! After completely confusing myself over what the alcohol was in the last question and losing like 2 marks (maybe 3 if they don't have ECF for the ester) and then 2 for the tertiary alcohol one, I'm in rather a state.
Original post by TitchTheAntiHero
identify doesn't have to mean the names,
I put the structures and names to be sure,

and I think an ion peak on the last question was useful, helped you to work out where the OH should go, as there was a peak at 31 which would be a CH2OH fragment which means the OH must be on the end,
I hope theres a mark for that


I used the large peak at 31 as well for this purpose, hopefully we get another mark there!
Reply 796
Avatar for Kir4nK
Kir4nK
7
Original post by Flint_09
Wikipedia!
"Methanol (one carbon), the propanols (three carbons giving two isomers), and the butanols (four carbons, four isomers) are all commonly found alcohols — these three toxic alcohols should never be consumed in any form."


wiki is not always right lol ?
Original post by Small123
For the last question, did you actually have to draw the structures? I swear it just said to identify the compounds, there didn't seem to be any explicit mention of drawing the structures in the question from what I remember, anyone able to clarify?


i REALLY hope we didnt have to draw the structures..... i dont think it said that?? :confused:
Original post by Abused Tampon
what did people get for the question about the enthalpy change of amonia? N2 + H2 ----> NH3
with Delta H = - or +66
and what was the answer?


i put +33
because the definition of the enthalpy change of formation is to make one mole and in the equation there was 2 moles produced so i divided by 2
Original post by SmithytheDrummer
I'm so sorry! After completely confusing myself over what the alcohol was in the last question and losing like 2 marks (maybe 3 if they don't have ECF for the ester) and then 2 for the tertiary alcohol one, I'm in rather a state.


Don't worry too much about it. I've done quite a few past papers on these, and the last one I did, an A required 77 marks. The others were all lower, from 72-75!

There is quite a bit you can afford to expend, even on silly things. I made many myself!

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